OK, took awile figuring it out. The truck on the long hood can be left on, the weight in the center can be left alone too. As you've already discovered the trucks are held in place little tabs on the trucks mating with slots in the shell. Get yourself a few flat toothpicks or some similar sized materials. Using a small sized screw driver or the tip of a knife blade pry the shell away from one tab then put a tooth pick so the tab cannot reinsert itself back into the slot. On the same side, do the same to the rear tab and inserting the tooth pick. (Now I don't know why or how, but without the tooth picks, soon as you pry the opposite side the darn tabs will re insert themselves back inro the slots and you'd be back to square one.) Now pry the tabs on the other side away from their slots and the truck will fall out.
Good luck, when prying don't over do it
Cheers
Willis